Dyeing of cellulose acetate fabrics with direct dyeing dyestuffs, lower aliphatic alcohols and lower aliphatic acids



Patented Oct. 14, 1947 DYEING OF CELLULOSE ACETATE FABRICS WITH DIRECT DYEING DYESTUFFS, LOW- ER ALIPHATIC ALCOHOLS AND LOWER ALIPHATIC ACIDS Cyril M. Croft and Walter H. Hindle, Cumberland, Md., assignors to Celanese Corporation of America, a corporation of Delaware i No Drawing. Application May 15, 1943,

Serial No. 487,128

5 Claims. 1

This invention relates to the dyeing of organic derivative of cellulose textile materials and relates more particularly to the dyeing of organic derivative of cellulos textil materials by mechanical impregnation methods.

An object of our invention is the rovision of an improved process for the dyeing of organic derivative of cellulose materials in medium to heavy shades.

Another object of our invention is to dye organic derivative of cellulose materials rapidly and economically with improved color yields.

Other objects of our invention will appear from. the following detailed description.

In the coloration of textile materials by means of dye baths it is highly desirable that the depth of shade desired in the textile material b reached with as short an immersion time and as little handling of the material as possible. When dyeing organic derivative of cellulose textile materials, however, it has been found that these materials are dyed more slowly than other textile materials since they are less absorbent and the dye liquor in the dye bath does not penetrate them as rapidly or as completely as other textile materials. Many dyestuffs, when applied to organic derivative of cellulose materials from aqueous baths, yield dyeings which are far from satisfactory. Consequently, long periods of immersion and manipulation are usually required in order to dye the textile materials in suflicientl deep, non-fugitive shades, which do not wash down to lighter shades when the dyed materials are subjected to washing operations subsequent to dyeing.

We have now discovered that organic derivativ of cellulose textile materials may be dyed rapidly in deep, uniform, level shades with direct dyeing dyestuffs for said organic derivative of cellulose materials if a lower aliphatic acid is present in the alcoholic solution of the dyestuff which is normally applied to the textile material by mechanical impregnation methods. By our novel process a substantial increase in the rate of production is made possible, and there may be obtained satisfactory dyeings with a minimum manipulation of the materials, as Well as shades which are deeper than were heretofore obtainable with a given concentration of dyestuffs in the dyebath.

The lower aliphatic alcohols which are suitable for use in the dye bath may be those alcohols which are solvents for the dyestuffs employed and which exert at least a swelling or softening action on the organic derivatives of cellulose. .While we prefer to employ ethyl alcohol in the dye liquor, other alcohols such as methyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, secondary butyl alcohol, tertiary butyl alcohol, n-amyl alcohol, secondary amyl alcohol and tertiary amyl alcohol, or mixtures of these alcohols may be used. The amount of the alcohol used in the dye liquor will var depending upon the 3,100: hol or alcohols used. We have found that optimum results are obtained when the lower aliphatic alcohol comprises at least by weight of th dye bath.

Any suitable lower aliphatic acid may be employed in accordance with our invention. Examples of such acids are acetic acid, propionic acid, or butyric acid. The acid may be employed in amounts Varying from 1 to about 8%, by weight, optimum results being achieved, however, when the acid is present in the dye bath in amounts of from 4 to 5% by weight.

Various direct dyeing dyestuffs for organic derivative of cellulose materials may be employed. By the term direct dyeing dyestuffs We mean to include all those dyes which produce their ultimate shade on the material being dyed without any preor after-treatment designed to effect a chemical change in the structure of the dye or the character of the material being dyed. These direct dyeing dyestuiis may be acid dyes which are ordinarily used for the dyeing of wool, as well as those dyes which are relatively insoluble in water and are usually applied to organic derivative of cellulose materials in the form of aqueous dispersions. When these dyestuffs are applied to organic derivative of cellulose textil materials by mechanical impregnation methods in alcoholic solutions containing a lower aliphatic acid in accordance with our process, the resulting dyeings are of uniform. depth and unusual brilliance and may be obtained with relatively short immersion times. An outstanding advantage of our novel dyeing process is that substantially increased color values may be obtained. In some instances the depth of shade may be increased as much as 200% over a dyeing obtained by the usual dyeing processes which do not employ lower aliphatic acids in the dyebath. Furthermore, th washdown of the shade in subsequent Washing and finishing operations is considerably less in the case of fabrics dyed by our novel process than in the case of fabrics dyed by prior processes.

The amount of dyestuff dissolved in the dye bath will vary with the final shade desired in the material which is being dyed and may be-from as low as 0.1% up to 6% based on the weight of the material to be dyed. V

The dye bath maybe applied to the organic derivative of cellulose textile meaterials by padding, spraying or by other convenient method or mechanical impregnation. Thus, as a continuous process, a fabric may be unwound from a roll, passed through a solution of the dyestuff, then between nipping rolls of a padding mangle which are adjusted to permit the desired amount of dye liquor to be retained in the fabric, and the fabric then subjected to ra id drying. The period of immersion of the fabric in the dye liquor is relatively short and may be from 1 to 4 seconds. If desire, the fabric may be processed throughthe padding mangle at speeds ranging up to 45 yards per minute.

Our process is applicable not only to the dyethere is circulated air heated to temperatures up to about 95 C. for quite rapid drying, and heating to say, 70 C. to 90 C., for less rapid drying. Advantageously, we dry the organic derivative of cellulose materials as rapidly as possible. While drying by means of heated air is preferable, heated drums or cans may also be used. Following the drying step, the dyed materials are usually washed and an aqueous bath containing about 0.1% of soap, or more, has been found to be satisfactory. A small amount of soda ash, say .02%, may also be added to the scouring bath.

The organic derivative of cellulose fabrics, staple fiber yarns or other textile materials which may be dyed in acordance with our process may 7 have a basis of cellulose esters or cellulose ethers. Examples of cellulose esters are cellulose acetate, cellulose propionate, cellulose butyrate, and mixed esters such as cellulose acetate-propionate and cellulose acetate-butyrate, while examples oi cellulose ethers are ethyl cellulose and benzyl cellulose. The materials may be mixed materials containing organic derivatives of cellulose and yarns or fibers of other materials such as cotton, silk, wool, or regenerated cellulose and in this way differential dyeings may be obtained where the dyes used have an affinity for only one of the components of the mixed textile material. Especially valuable differential dyeings or cross-dyed effects may be obtained on fabrics containing mixed cellulose acetate and wool yarns when specially solubilized, dispersed dyes having no affinity for the wool are employed. The cellulose acetate fibers may be dyed fairly heavy shades while the wool fibers remain uncolored and unstained. If desired, the wool fibers may later by dyed with dyestuffs which have affinity for the wool or the wool may be left uncolored.

In order to further illustrate our invention but without being limited theret the following examples are given: I

. 4 Example I 60 parts by weight of 6-chlor-2z4-dinitro-benzene-azo-2-amino bis omega-hydroxyethyl-4- acetylamino 'anisole and 2 partsgby i'weight of 4-nitrobehzene-azo 2 acetylamino -4 di-hydroxyethyl-amino-benzene are sifted into 42 parts by weight of glacial acetic acid. To this mixture are added parts by weight of ethyl alcohol. To the resulting solution are then added 250 parts by weight of water and 480 parts by weight of ethyl alcohol. A cellulose acetate fabric is pad-dyed employing this dye bath and the dyed fabric dried rapidly at to C. A fabric dyed in a deep blue shade is obtained. When washed for example in a 1 gram per liter aqueous soap solution containing 0.25 gram per liter, of soda ash, the dyed fabric exhibits very little loss in shade due to wash-down. The shade obtained by a single padding operation is quite heavy and a single pass is usually sufficient.

- Example II 5 parts by weight of blue acid wool dye (Color Index No. 671) are dissolved in 52.5 parts by weight of glacial acetic acid and 80 parts by weight of ethyl alcohol are added thereto. To this solution are added 250 parts by weight of water and 480 parts by weight of ethyl, alcohol. A cellulose acetate fabric is pad-dyed employing this dye bath and dried rapidly at 90 to 95 C. The fabric is dyed in a deep blue shade. The dyed fabric is washed asin Example I. In a single pass through'the dye bath, the fabric is dyed a shade 200% deeper than that obtainable when the dyebath does not contain acetic acid and the dyed fabric exhibits very little washdown in the washing and scouring operation.

It is to be understood that the foregoing detailed description is given'us merely by way of illustration and that many variations may be made therein without departing from the spirit of our. invention.

Having described our invention, what we desire to secure by Letters Patent is:

1. Method for the coloration of a cellulose acetate textile material which comprises mechanically impregnating such cellulose acetate textile material with a solution of a direct dyeing dyestuff for the cellulose acetate material in an aqueous medium comprising at least 60% by weight of a lower aliphatic alcohol, said solution containing from 1 to 8% of a lower aliphatic acid, and then rapidly drying said material.

2. Method for the coloration of a cellulose acetate textile material which comprises mechanically impregnating such cellulose acetate textile material with a solution of a direct dyeing dyestuff for the cellulose acetate material in an aqueous medium comprising at least 60% by Weight of ethyl alcohol, said solution containing from 1' to 8% of acetic acid, and then rapidly drying said material. 7 Y

3. Method for the coloration of a fabric containing'yarns of cellulose acetate which comprises padding thefabric with, a solution of a direct dyeing dyestuif for the. cellulose acetate material in an aqueous medium. comprisingat least 60% by weight of'a lower aliphatic alcohol, said solution containing from 1 to 8% of, acetic acid, and then rapidly drying said fabric.

4. Method forthe coloration of a fabric containing yarns of cellulose acetate which comprises padding the fabric with a solution of a direct dyeing .dyestuff for the cellulose acetate material in a medium comprising 65% by weight of ethyl alcohol, 5% of acetic acid and 30% of Water, and then rapidly drying said fabric.

5. Method for the coloration of the cellulose acetate in a textile material containing fibers of cellulose acetate and wool fibers which comprises mechanically impregnating said textile material with a solution of a direct dyeing dyestufi for the cellulose acetate material in an aqueous medium comprising at least 60% by weight of a lower aliphatic alcohol, said solution containing from 1 to 8% of a lower aliphatic acid, and then rapidly drying said material.

CYRIL M. CROFT. WALTER H. HINDLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,292,433 Croft Aug. 11, 1942 1,927,145 Whitehead Sept. 19, 1933 2,218,628 Sowter Oct. 22, 1940 1,968,819 Dreyfus Aug. 7, 1934 2,344,973 Croft Mar. 28, 1944 FOREIGN PATENTS Number Country Date 500,960 Great Britain Feb. 17, 1939 412,952 Great Britain July 5, 1934 

